1. Field of the Invention
The present invention relates to information processing apparatuses, information processing methods, information recording media, and computer programs. More particularly, the invention relates to an information processing apparatus, an information processing method, an information recording medium, and a computer program in which a playback path is defined in accordance with the information processing apparatus so that content having a playlist selected for each playback zone can be seamlessly played back.
2. Description of the Related Art
Various software data (hereinafter referred to as “content”), such as audio data, e.g., music, image data, e.g., movies, game programs, and various application programs, can be stored on recording media, for example, Blu-ray discs (trademark) using blue laser light, digital versatile discs (DVDs), mini discs (MDs), compact discs (CDs), as digital data. In particular, Blu-ray discs (trademark) using blue laser light are high-density recording discs and can record a large volume of video content as high-quality image data.
Digital content is stored in various information recording media, such as those described above, and is provided to users. A user uses the digital content by playing it back on the user's personal computer (PC) or a player, such as a disc player.
Generally, the distribution rights of many content data, such as music data and image data, are owned by creators or sellers of such content data. Basically, therefore, certain usage restrictions are imposed when distributing content, that is, the use of content is allowed only for authorized users, thereby preventing unauthorized copying.
According to digital recording apparatuses and recording media, images and sound can be repeatedly recorded and played back without a loss in quality. Thus, the distribution of illegally copied content via the Internet, the circulation of recording media, such as compact disc recordable (CD-R) discs, recording copied content thereon, so-called “pirated discs”, and the use of copied content stored in hard disks of, for example, PCs, are widespread.
DVDs or large-capacity recording media, such as those using blue laser light which have recently been developed, can record a large volume of data, for example, up to several movies, on one medium, as digital information. Since video information can be recorded as digital information as described above, it is becoming important to perform copyright protection by preventing unauthorized copying. Nowadays, to prevent unauthorized copying of digital data, various techniques for preventing unauthorized copying are practically applied to digital recording apparatuses or recording media.
For example, in DVD players, a content scrambling system is employed. According to the content scrambling system, data, such as, video data or sound data, encrypted and recorded on, for example, a DVD read only memory (DVD-ROM), can be descrambled for playing back the content.
In descramble processing, it is necessary to execute processing using specific data, such as a key, provided for licensed DVD players. A license is given to DVD players that are designed in compliance with predetermined operation rules, for example, agreeing not to perform unauthorized copying. Accordingly, licensed DVD players can descramble data recorded on a DVD-ROM by using specific data, for example, a given key, to play back images or sound from the DVD-ROM.
On the other hand, an unlicensed DVD player cannot play back data recorded on the DVD-ROM since it does not have a key for descrambling the scrambled data. In this manner, in the content scrambling system, DVD players that do not satisfy conditions demanded for receiving a license cannot play back digital data from the DVD-ROM, thereby preventing unauthorized copying.
However, such a content scrambling system is not a perfect system, and there are many content scrambling systems whose descrambling methods have already been deciphered and are distributed via communication means, such as the Internet. In this manner, once scrambling methods are deciphered, content is illegally played back or copied by unauthorized descramble processing, and the copyright or the right to use content is violated.
As another technique for preventing the unauthorized use of content, the published Japanese translations of PCT international publication for patent application No. 2004-532495 discloses a configuration in which video data having different content variations are set and one piece of video data having a specific content variation is selected. According to this configuration, however, content can be played back in many devices due to leakage of a cryptographic key, in which case, it is difficult to specify the source of leakage.